The invention concerns a hydraulic coupling socket with a housing, in particular an axially extending sleeve holding an axially, preferably coaxial, plunger, an axially movable pusher sleeve that surrounds the plunger, preferably coaxially, and an axially movable retaining sleeve surrounding the pusher sleeve, also preferably coaxially, whose surface radially braces or frees latch elements mounted in the housing, the in particular annular end face of the retaining sleeve lying coplanar with the end faces of the plunger and the housing in a decoupled position.
Hydraulic coupling sockets of this type are known from the prior art, and are used in conjunction with similar hydraulic coupling plugs, such that the plug and the socket can be coupled with one another in order to conduct a hydraulic fluid.
Couplings of this type are used, for example in order to connect an existing hydraulic circuit in a relatively fast and easy manner with various tools, or to disconnect it from them. For example, they are used in agricultural and construction machine construction in order to conduct hydraulic oil from one hydraulic pump to a tool and back to a recovery tank.
The known design of such hydraulic coupling sockets is such that the plunger extends axially so as to be in a fixed coaxial position in the housing, and has an outer, roughly circular end face.
In a design known to the prior art, the area facing away from the end face of the plunger forms a seat surface that can interact with a rear free end of the above-described pusher sleeve in order to close the inside of the pusher sleeve to the passage of fluid when the axially movable pusher sleeve is moved axially from the side facing away from the end face, and thus from the inside of the housing toward a hydraulic coupling plug, and is lying on the plunger.
In this prior-art design, the working hydraulic fluid is applied to the interior of the outer area of the pusher sleeve that interacts with a plunger, such that this fluid can only flow into a connected hydraulic coupling plug if the pusher sleeve has moved axially away from the plunger or its seat surface. To this end, in the prior-art hydraulic coupling sockets, the pusher sleeve is axially movable in the housing, such that the fluid passage can optionally be opened and closed. In this design, the pusher sleeve is a passage for the hydraulic fluid to be conducted, which can be closed by relative movement between the pusher sleeve and the plunger. This passage holds the plunger that is surrounded by the hydraulic fluid to be conducted.
As described below with regard to the invention, the fluid passage can also be designed differently, although it is also essential here for the fluid passage to be able to be closed or opened by relative axial movement between the sleeve and the plunger.
In the prior art a retaining sleeve coaxially surrounds the pusher sleeve and the plunger, and has an annular end face surrounding the plunger, which, when decoupled, is coplanar with the end face of the plunger and the end face of the outer housing, such that a decoupled hydraulic coupling socket has a substantially flat, smooth outer surface on its end.
The retaining sleeve can be moved in particular against a prestressing spring force axially into the housing, and, when decoupled and over part of its movement path, supports latch elements that are radially movable within the wall of the housing, in particular in the area of the outer end that faces a hydraulic coupling plug, whereby such latch elements are, for example balls.
“Movement into the housing” refers here and below in the description of the invention to the fact that movement of the respective element goes toward the fluid supply of the hydraulic coupling socket, i.e. in particular away from a hydraulic coupling plug to be coupled.
By inserting a hydraulic coupling plug into the socket, the plunger, which is fixed in the prior art, and a corresponding plunger of the hydraulic coupling plug come into contact with one another such that the hydraulic coupling plug moves axially into its housing to cause an outer housing area to move the retaining sleeve and be inserted further into the housing, thus opening, with respect to the plug whose plunger is moving inside the housing, a fluid passage in the hydraulic coupling plug.
By inserting the housing sufficiently far into the housing, the retaining sleeve is moved so far axially into the housing that its end face is no longer supported by the latch elements, which, upon further movement, lie on the outer surface of the housing, until the housing is inserted into the housing up to a ring groove on this surface, such that the latch elements, for example balls, can engage with this ring groove, for example fall into it. In such a position, the plug is axially secured in the socket, whereby accidental separation of the plug from the socket can be prevented by holding the latch elements in the engaged position with the groove of the housing by a sliding sleeve (for example under spring tension) on the outside of the housing.
When the housing is inserted into the housing, once the retaining sleeve around the pusher sleeve has been moved a certain distance, the retaining sleeve moves onto a limit stop of the pusher sleeve, such that, for the rest of the path of insertion of the plug into the socket, the axially moved retaining sleeve simultaneously moves the pusher sleeve, such that its free outer end moves away from the sealing area of the plunger, thus opening the fluid passage.
In order to achieve the axial movements described here, in the prior art, in particular also in the case of the invention described below, the individual movable parts are preferably coaxial to one another and positioned in or on one another. In the invention, an axially parallel, non-coaxial arrangement of the parts to one another is also possible.
For example, the movability of the retaining sleeve arises from the fact that its external diameter is such relative the internal diameter of the housing that they can slide on one another. Likewise, the pusher sleeve can be positioned with an external contact area of the inner wall of the retaining sleeve and/or an additional internal area of the housing for axial movement.
Movement is such that, in the prior-art design, the hydraulic fluid supplied to the socket through a hydraulic connection can enter into the pusher sleeve, and can only move into a plug after removing the pusher sleeve from the seat surface of the plunger.
One disadvantage of the prior-art hydraulic coupling socket is considered to be the fact that, due to the existing movement paths, the pusher sleeve is already moved, thus opening the fluid passage to the plug, even if the plug is not yet securely fastened on it by interlocking with the latch elements in the housing. This allows hydraulic fluid to exit the socket, which may harm the environment.
An additional disadvantage is considered to be the fact that, on the one hand, plugs of a prior-art design must be moved with an axially movable plunger with respect to an external housing against the fluid pressure inside the plug when coupling, and, on the other, starting on the above-described path of movement of the retaining sleeve, by which it comes into contact with the pusher sleeve, movement of the plug must also move the pusher sleeve against the pressure within the socket of the hydraulic fluid to be moved. In the prior-art designs of the hydraulic coupling socket, the pressure of the hydraulic fluid to be moved acts on the annular end face of the pusher sleeve on the side of the hydraulic fluid connection, thus, together with any dilated surfaces of the pusher sleeve, causes significant forces axially toward the end face of the plunger or he plug, which counteract movement of the pusher sleeve by the plug.
This must be considered a disadvantage, inasmuch as it is impossible for the operator to manually generate the forces necessary in lines that are under pressure. Thus, normally it is necessary when coupling, first to decompress the hydraulic system in order to allow for the plunger to move into the housing and the pusher sleeve to move into the housing.